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Abstract
Historic handling of explosives has led to worldwide contamination of soils with 2,4,6-trinitrotoluene (TNT) and heavy metals as well. In this study, the combined effects of TNT and lead on soil microbial communities were analyzed. Theresa and Appling soil samples were spiked with up to 365 mg kg-1 TNT, 25 mg kg-1 Pb, and a mixture of both compounds at similar concentrations and incubated for 15 d. Changes in microbial respiration, biomass, total and bioavailable TNT, bioavailable Pb, and community composition with time were monitored. The presence of Pb did not affect TNT transformation at a concentration less than 365 mg kg-1. All treatments negatively affected biomass production in Appling soil, while Theresa biomass production increased with increasing TNT concentration. Fatty acid methyl ester (FAME) analysis showed that 365 mg kg-1 TNT negatively affected bacteria and fungi in both soils. In Appling soil, 365 mg kg-1 TNT mixed with Pb favored an increase in bacteria while fungi decreased. Mixes of 25 mg kg-1 Pb and 365 mg kg-1 TNT negatively affected bacterial and fungal abundance in Theresa soil. This study showed that different soil microbial communities respond differently to TNT and Pb contamination.